Field of the Invention
Embodiments of the present invention generally relate to a method and system for acoustic echo cancellation using cascaded Kalman filtering.
Description of the Related Art
Acoustic echo cancellation (AEC) has been an area of active research for the past many decades. As AEC is implemented in newer and sophisticated devices, it is expected that its performance is also improved over the devices of prior generation. Various aspects of AEC have been investigated in the past; this includes double-talk, convergence, stereo-echo cancellation, etc. One of the issues that has limited the performance of a practical echo canceller is non-linearity of the echo path. A typical echo canceller is designed assuming that the echo path is linear and modeled by a linear finite impulse response (FIR) filter. Consequently, the echo cancelling filter is also modeled as linear. In practical applications, like cell phones, the echo path is non-linear because of imperfections introduced by the data converter, amplifier and the loudspeaker operating close to saturation. Attempting to cancel non-linear echo using a linear FIR filter leaves residual echo in the uplink signal resulting in annoying user experience.
Several methods have been proposed in the past to address the non-linear echo cancellation. Popular among them are the Volterra filter based methods. These methods, however, suffer from high complexity because of large number of filter parameters to adapt. A large class of methods started with an assumption of a non-linear model. There are mainly two such models; memoryless non-linearity is used for smaller loudspeakers used in portable hand-held devices like cell phones. On the other hand, non-linearity with memory is generally employed in high-end audio devices like precision audio systems.
Therefore, there is a need for a method and/or system for an improved acoustic echo cancellation in the presence of unavoidable non-linearity in the echo path.